fix tyToExtend() (#21628)

Author: WalterBright

compiler/src/dmd/backend/arm/cod2.d

@@ -201,6 +201,7 @@ void cdorth(ref CGstate cg, ref CodeBuilder cdb,elem* e,ref regm_t pretregs)
 Extend tyToExtend(tym_t ty)
 {
     //debug printf("ty: %s\n", tym_str(ty));
+    ty = tybasic(ty);
     assert(tyintegral(ty) || ty == TYnptr);
     Extend extend;
     const sz = tysize(ty);